Abstract

Anatomical study of the leaf epidermis in 6 tuber species namely Manihot esculenta Crantz, Cyperus esculentus Linn. Ipomoea batatas Linn., Xanthosoma sagittifolium Schott, Colocasia esculenta Schott and Caladium hortulanum Vent was conducted. Among these species, only C. esculenta has epistomatic leaves with stomata occurring only on the adaxial or upper surface of the leaf. The remaining 5 species have amphistomatic leaves, with stomata on both surfaces of the leaf. M. esculenta, C. esculentus and I. batatas have paracytic stomatal complex type with a frequency of 100%, while X. sagittifolium, C. esculenta and C.hortulanum have brachy-paracytic stomatal complex type with a frequency of 100%. Species with stomatal density range of 22 - 26 stomata per square millimetre, namely I. batatas, X. sagittifolium, C. esculentus and C. esculenta were the most transpiring with high potentials for humidification of the atmosphere. Those species with the density range of 16 - 21 stomata per square millimetre, namely C. hortulanum and M. esculenta were the least transpiring with low humidification potentials. There was no positive correlation between stomatal size and transpiration rate as C. hortulanum with the highest stomatal size had the least rate of transpiration. However, stomatal index, that is, the % spread of stomata was positively correlated with transpiration as I. batatas with the highest stomatal index of 20.94 had the highest rate of transpiration. Massive cultivation of these tuberous species through intercropping with tree species may help in combating drought and desertification processes. Since these tubers with the exception of C. hortulanum are edible, there is added advantage of increased food production, through this suggested cropping system. I. batatas being a creeping plant can also be a useful cover crop as part of conservation measures for desertified or exposed areas.   

Key words: Tuber species, stomatal complex types, transpiration.